A piston type air compressor for producing compressed air includes an air compression pump, a motor to drive the air compression pump, driving belt pulleys mounted to the motor and the air compression pump, a belt to connect the belt pulleys to each other such that the air compression pump is driven due to the rotational power of the motor.
In order to radiate and cool compression heat of the air compression pump, the belt pulley which is mounted to the air compression pump is made in the form of a fan and cooling wind is generated only when the fan-shaped belt pulley must be rotated in a predetermined direction. The driving belt and the belt pulleys are surrounded by a safety net to guarantee safety during the driving of the air compressor.
The piston type air compressor, constructed by the common components, according to the related art may be divided into one in which single type compression cylinders are arranged on a cylinder case in the radial direction and the other in which parallel type compression cylinders are arranged in a single row or multiple rows.
Here, the single type cylinders in which the compression cylinders are arranged in the radial direction, as illustrated in FIG. 8A, employs a single-pin crankshaft 10. The single-pin crankshaft 10 includes a balance weight 12 integrally formed at a leading end of a rotation shaft 11 to maintain a rotation balance of the rotation shaft 11, and a rod coupling unit 13, which is eccentrically coupled to a side of the balance weight 12 and to which bid-ends of a plurality of connecting rods connected to the insides of the respective compression cylinders are connected. The rotation shaft 11 is installed to the rod coupling unit 13 by a connecting member 14.
Thus, the plurality of the connecting rods coupled to the rod coupling unit 13 are arranged in the radial direction so that the compression cylinders are arranged in the compression pump in the radial direction and an excellent air cooling performance can exhibit.
Moreover, the parallel type cylinder, as illustrated in FIG. 8B, employs a dual-pin crankshaft 20. The dual-pin crankshaft 20 includes a balance weight 22 integrally formed at a leading end of a rotation shaft 21 to maintain a rotation balance of the rotation shaft 21, a rod coupling unit 23, which is eccentrically coupled to a side of the balance weight 22 and to which bid-ends of a plurality of connecting rods connected to the insides of the respective compression cylinders are connected, and another rod coupling unit 23a installed to the leading end of the rod coupling unit 23 to form a step by a connecting member 24. The rotation shaft 21 is installed to the leading end of the rod coupling unit 23a by the connecting member 24.
Thus, a pair of the rod coupling units 23 and 23a form a zigzag shape so that the top dead centers and the bottom dead centers of the connecting rods which are coupled with the rod coupling units are symmetrically arranged and the pressurizing and vacuuming phenomena can be cancelled during the running of the compression pump. Absolute load positions of the respective compression cylinders are symmetrically arranged so that excellent driving power of the motor can exhibit.
On the other hand, different from the single-pin crankshaft 10 and the dual-pin crankshaft 20, as illustrated in FIG. 8C, since a pinless crankshaft 30 is directly installed to a motor in an integrated-motor type air compressor employing the pinless crankshaft 30, the belt pulleys, the belt, and the safety net as the driving devices can be eliminated.
Consequently, since various types of crankshafts employed in the existing piston type air compressor are used only for respective air compressor suitable for features of the respective air compressors, individual effects exhibit, but the union of the above-mentioned effects cannot exhibit.
In other words, a crankshaft having all the advantages of the single-pin crankshaft, the dual-pin crankshaft, and the pinless crankshaft cannot be accomplished by the present technology, because the usual crankshaft has technical limit in employing the connecting member to connect the rod coupling units with each other and the balance weight to maintain the balance during the rotation.